Asterisk SIP behind Pix firewall

[vince62s]

Hi there,,
Here is my problem:

I setup Asterisk (PBX /SIP) behind a pix firewall with Nat.

My VOIP phone on the LAN register fine with Asterisk.

My IP Phone trying to register from outside (internet behind or not behind another firewall) fail to register on the SIP server of Asterisk.

I tried several conf but I know pretty well the access list, alias and static between Public IP and LAN IP.
When I scan UDP port 5060 it is open
When I look at the log of the IP client phone, I see the exchanges between client and server.

BUT I do not understand why the registration fails.

any clue?

 

[jasonswan]

A quick thoguth is have you enabled the application layer inspection on the PIX

try

fixup protocol sip udp

let me know if that helps I am curious....